Method of forming lasts.



E. J. PRINDLE.

METHOD OF FORMING LASTS. I APPLICATION run]: AUG.14, 190 1. nn'xnwnn mi.20, 1 10. I Patented Aug. 23, 1910.

3 BHEETB BHEET 1.

E. J. PRINDLE. mm non 0E FoRMmGLAsTs. APPLICATION FILED AUG. 14, 1901.RENEWED UK. 20, 1910.

968,409. Patented Aug. 23, 1910..

' k 3 SHEETS-SHEET 2. w m 4 w- E. J. PRINDLB. 7 METHOD or romaine ms'rs.APPLIUATION TILED AUG. 14, 1901. RENEWED JAN. 20, 1910. 968,409.Patented Aug. 23, 1910.

8 HEIGHTS-SHEET 3.

G n 601mm 5 UNITED STATES PATENT OFFICE:

EDWIN J. PRINDLE, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR, BYMESNE ASSIGNMENTS, TO UNITED SHOE MACHINERY COMPANY, OF PATERSON, NEWJER- SEY, A CORPORATION OF NEW JERSEY.

METHOD OF FORMING LASTS.

Specification of Letters Patent. Patented Aug. 23, 1910.

Application filed August 14, 1901, Serial No. 72,060. Renewed January20, 1910. Serial No. 539,140.

To all whom it may concern:

Be it known that- I, EDWIN J. PRINDLE, of \Vashington, in the Districtof Columbia, have invented certain new and useful Improvements inMethods of Forming Lasts, and do hereby declare that the following is afull, clear, and exact description thereof, reference being had to theaccompanying drawings, in which- Figures 1 and 2 are respectively afront and a side elevation of a dog adapted for use in practicing mymethod; Fig. 3 is a side elevation of a wedge which is adapted for usein securing fore parts of lasts or the blocks from which such fore partsare to be formed to the dog illustrated in Fig. 1; Fig. 4 is a sideelevation of the dog illustrated in Fig. 1, and a block from which afore part of a last is to be formed, such block being secured on saiddog; Fig. 5 is a side elevation of the dog illustrated in Fig. 1, and afore part of a last, such fore part being secured on said dog; Fig. 6 isa side elevation of a model fore and heel part showing their relativedirections of rotation; Fig. 7 is an end view of a last partillustrating the distortions produced by the last lathe, and Fig. S is aside elevation of a model ancka larger last reproduced therefrom,illustrating the error introduced by the incorrect positioning of themodel with reference to the axis of the head stock spindle and Fig. 9 isa diagram also illustrating the error shown by Fig. 8 and Fig. 10 is adiagrammatic view of the swing frame of a lathe being used in thepractice of my invention.

Letters of like name and kind refer to like parts in each of thefigures.

st m The object of my invention has been to devise a method of forminglasts, by the use of which the foot shape contour of lasts, or the partsof lasts, can be readily formed, par ticularly at the extremities, andby the use of which the surfaces of divided lasts that are within theoutlines of the last can be formed in accurate relation to thefoot-shape contours thereof, so that the parts of a last, whenassembled, shall have precisely the desired relation, and together shallform a last of precisely the desired contour, and to such ends, myinvention consists in the method of forming lasts, substantially ashereinafter specified.

Vhile my method is applicable to the turning of whole lasts in onepiece, I prefer to illustrate it by its application to theinterchangeable fore-part shown in my Patent No. (H8525, granted May1st, 1900, to which reference is made for a full description of suchpart. The model, where the process is used for the manufacture of wholelasts, will, of course, be a whole last. The model for the specificinstancewhich I have chosen will, of course, consist of a fore-part anda heel-part constructed as described in the said patent.

The blanks or blocks D, from which the fore and heel parts are to beturned may be formed by cutting up a rough block so that such blanksshall have all the geometric surfaces which the finished parts are tohave, and shall be complete except for their footshape contours.

To attach the model fore part to the model head stock spindle of theordinary last turning lathe, (such for instance, as that illustrated inthe patent to J. E. Kimball, No. 546,160, September 10th, 1895,) Iprovide a dog B, consisting of a tapered shank I) having a screw thread12 at its larger end, and beyond such thread having a plate 6 formedthereon, substantially perpendicular to the axis of the shank b. A plate29 projects from the face of the plate 6 in aplane perpendicularthereto, and such plate corresponds to the portion of the fore partplate of the last forming part of a means for uniting the fore-part ofthe last with the heel part to make a complete last, which is receivedin. the fore part A thereof, past its rear surface A Such plate I) hasan arcshape forward edge 0* along which extends an arc-shape flange 6said plate being adapted to fit into the slot A of the fore part and tohave its flange I) received in a corresponding arc-shape groove thereof.In the plate o an opening I) is formed to permit the passage of thewedge E of the in the arc-shape groove of such fore part. The wedge E isthen inserted from the rear through the opening 6 and into the slot A inthe fore part until its spring E engages the notched ear 5 such actionwedging the plate 6 against a wall of the slot A and fastening the forepart firmly to the dog. If the dog be not already screwed or driven intoits socket in the model head-stock spindle, it is secured in suchsocket, and the fore part is thus firmly mounted on the spindle and insuch position that its entire outer surface is exposed to the action ofthe guide wheel. The block D is then attached to its dog B in the samemanner as was the model fore part attached to the dog B. The dog F isthen secured to the work head-stock spindle of the lathe, and the blockD is thus supported in the lathe so that its entire surface, except therear surface d, corresponding to the surface A in the finished last, isexposed to the action of the cutter. Care must be taken to have the dogsparallel on the two spindles in every particular, in order that thegeometric surfaces in the new fore part shall have the same relation tothe foot shape contour thereof as do the similar surfaces in the modelto the foot shape contour thereof.

The cutters of the lathe should be so adjusted that the outermost orfinishing cutter will be nearer to the curve of the toe of the last,when operating thereon, than any of the other cutters, so that its workwill not be destroyed by the subsequent cutters.

On setting the lathe in motion, the new fore part can be entirelyfinished, including the toe, since the toe of the model and the portionof the block which is to form the toe of the new fore part arecompletely exposed to the action of the guide wheel and of the cutter,respectively.

Owing to the spring of the swing frame of the lathe, when the guidewheel rises toward the end of a transverse depression in the lastsurface, and thus recedes from the axis on which the last is revolving,the lathe will cut away too much from the block being turned. On theother hand, as the guide wheel passes over the crest of the comb orother elevation of the model, and thus approaches the axis on which thelast is revolving, inertia tends to throw it away from the surface ofthe last, carrying with it the cutter wheel, and thus adding to, orbuilding up, the last being formed at such point. This action isillustrated in Fig. 7, in which the full line represents the end of themodel fore or heel part, the dotted line f represents the shape which isformed by a right hand rotation as indicated by the arrow f and dottedline f represents the shape which is formed by a left hand rotation, asindicated by the arrow i In order to have the foot shape contours of thefore and heel parts come flush with each other, If cause the fore andheel part models to revolve in opposite direc tions at the same speed,when attached to the same head-stock spindle as indicated in Fig. 6,which is the same as saying that such parts revolve in the samedirection when looking toward the toe of the assembled last. The errorsthus occur in the same direction, and are thus rendered unobjectionableas the foot shape contours come flush with each other.

If desired, the model can be cut away where the excesses will occur inthe finished last part, and the model can be built up where the cuttingaway would occur in the finished last, so that the errorsof the lathewill produce a perfect last.

The last lathe in forming a last or last part longer or shorter than themodel, but of the same width, always reproduces a point in the last in aline passing through the point and parallel to the axis of the spindles.Thus if the tip of the toe of the model be in the said axis, thereproductions of such tip will all occur in said axis, no matter howmuch longer or shorter than the model the new last may be. For thisreason I so position the model on the spindle that as shown in Fig. 6the axis on which the model revolves will be parallel to the lines onwhich it is desired to reproduce the points of the model in grading fora longer or a shorter last. The axis on which the last revolves should,for instance, be substantially parallel to a plane tangent to the lowersurface of the heel of a shoe on the last and touching the sole of theshoe.

In Fig. 8 is illustrated in full lines a model revolving on an axis G,the axis being oblique to the plane before mentioned, and in dottedlines, a longer last of the same width as it would be reproduced by thelathe from the model when revolved on such axis. As before stated, thepoints of the model will be reproduced in lines parallel to the axis,and this action results in greatly J/ distorting the new last, causingits toe to be formed too much below its instep and its heel to be formedtoo much above its instep. This is clearly indicated by lines Gg and Ggdrawn through the insteps of the lasts and their toes. The angle G G gin the last being formed will be seen to be very far from equal to theangle G G g in the model, which angles should be equal. I am able toposition the model and blank fore parts as desired with reference to theaxis of the head-stock spindle by forming the surface (Z and plate 6 ofthe dog at the proper angles to the said axes.

The above described action of the last lathe, producing a distortedlast, when the model is positioned in the lathe, in the ordinary way, isfurther illustrated in Fig. 9. In such figure I and K represent,respectively, the ordinary toe and heel-dogs revolving on the axis L-M.The model N is supported, as usual, upon the heel-dog I and with its toen at the toe-dog K, so that the toe is substantially on the axis L-M. Aheel O is represented on the model, and the fioor line is seen touchingthe heel and the toe of the model. The floor line represents theposition of the floor relative to the model N, when the model is in ashoe standing upon the floor. If it is desired to produce a longer lastP, than the model N, the last P being of the same width as the model,all of the points of the model N will be reproduced in the new last atthe same distance from the axis L-M, as in the model because the cutterwill be the same distance from the axis as the model wheel, in allpositions. The result will be that the toe p of the last P will be onthe axis L-M, because the toe a of the model is on such axis. The crest7) of the comb of the last P will be in a line QR parallel to the axisL-M, and passing through the comb n of the model. The ball p of the lastP will be on a line RS parallel to the axis LM and touching the ball aof the model. The top of the toe p of the last P will be on a line TUparallel to the axis L-M. The result will be, that the floor line V-lVof the last P will be very considerably below the floor line of themodel, showing that the toe of the last P has been depressed in beingreproduced. The. normal last X, of a length corresponding to the lengthof the last P, should be projected forward, so to speak, upon linesparallel to the fioor line, instead of upon lines parallel to the axisL-l l. For instance, its ball a; should rest upon the floor line of themodel, its heel also resting upon such line; its toe 00 should be thesame distance above the floor line as the toe N of the model, the toe 50being in a line YU parallel to the floor line and passing through thetoe end of the model. The tip x of the toe of the last X should be in aline AB parallel to the floor line of the model, and touching the tip 11of the model. The crest of the comb m of the last X should be in a lineBO" parallel to the floor line of the model, and passing through thecrest n of the comb of the model. From this figure it can be seen, howthe inclined position of the model in the lathe, so that its floor lineis at an angle to the axis of revolution, re-

' sults in a serious distortion of lasts which are longer or shorterthan the model. The advantage of my mode of procedure, of placing thefloor line of the model parallel to the axis of revolution, is alsoapparent in that it causes the parts of the new last to be projectedforward in lines which are parallel with the axis of revolution.

As another means for carrying my method into practice, for thecompletion of an extremity of the last or last part an ordinarysliding-j aw chuck can be secured to the ordinary. model head stockspindle of a last turning lathe. The model, which may be an ent1re last,can be clamped either by the toe or heel by such chuck to its head stockspindle or by a stub or regular projection formed on or attached at thetoe or heel, leaving the opposite extremity exposed, and the block fromwhich the last is to be formed can be secured by its chuck to the workhead-stock spindle, leaving its opposite extremity exposed. The modeland block can then be revolved, and the guide wheel can travel along thebody of the model and over the entire exposed extremity thereof, thusguiding the cutter to form the body of a last from the block and tocomplete one extremity thereof. The model and the partly finished lastcan then be removed from the chucks and the unfinished extremity of thelast completed in any desired manner.

The practice of my method is further illustrated diagrammatically inFig. 10. Here the model toe-part A is supported upon the dog B and theblock C is supported upon the dog D the two dogs being supported in thelathe upon the same axis, as usual. The model wheel E operates againstthe model, and guides the cutter F in its formation of the new last. Thenew fore-part is shown as partly shaped from the block. Shoes are shownin dotted lines on the model and on the new last, and the floor line G Hof the model is shown parallel to the axis of the dogs. Therefore thefloor line I K of the new last will be parallel to the axis ofrevolution, and when the new last has a shoe heel applied to it of thesame height as the one on the model, the heel will set squarely on thefloor line when the ball of the new last touches the floor line, itsshould be the case in a properly made ast.

It is obvious that dogs corresponding to other forms of hinge mechanismfor lasts can be used to support the corresponding last parts in thelathe, and that such parts can be reproduced by my method.

The generic features in the present application which are common to myapplications #19,292, filed June 6, 1900, and #127,931, filed Oct. 20,1902, are not claimed herein, but are claimed in said applications.

Having thus described my invention, what I claim is 1. The method ofturning from models, lasts which shall be longer or shorter than suchmodels, which method consists in revolving a model on an axissubstantially parallel to the floor line of the model, and operating ona revolving block by a cutter guided from such model.

2. The method of turning from models, parts of a divided last, whichshall be longer in a last lathe, which consists in revolving the modelfore part and the model heel part 10 in opposite directions in the latheWhen viewed from their dividing surfaces toward their toe and heel,respectively, and shaping blocks from such models, substantially asdescribed.

In testimony that I claim the foregoing 15 I have hereunto set my handthis 14th day of August, 1901.

EDWIN J. PRINDLE.

Witnesses:

HENRY C. HAZARD, J AS. E. HUTOHINSON.

